The present invention relates to a golf club head, and more specifically, relates to a golf club head with improved material thickness on the inner surface of the face part.
The majority of the heads of recent wood clubs have at least the face part thereof formed of a metal material. The material thickness of the face part must be thick enough to maintain sufficient strength to withstand the impact with the ball. While heads are becoming larger, because of the rule that they must have a volume less than 460 cm3 plus a tolerance of 10 cm3, large heads that come very close to the upper limit of 460 cm3 account for the majority of driver heads.
When heads increase in size in this manner, because the face part becomes heavy, in order to both reduce the weight of the face part and maintain the strength of the face part, the material thickness of the face part is reduced and ribs are provided on the inner surface of the face part. For example, Japanese Patent Application Publication 2006-141806 discloses the provision of six ribs that extend from a center part of the face toward the periphery of the face.
Japanese Patent Application Publication 2008-36050 states that, when ribs are provided so as to form an X-shape at the center part of the inner surface of the face part, the repulsion performance of the face part when a ball is hit at a point away from the face center, at the sole side or crown side, is greatly reduced from the case of hitting the ball at the face center and, in order to solve this problem, describes making the material thicknesses in four divided surfaces on the inner surface of the face delineated by the ribs such that the thickness is less at the sole side and crown side than it is at the toe side and heel side.